Why Dark Matter May Have Self-Interactions

Dark matter makes up most of the matter in the Universe, yet its fundamental nature remains unknown. In this talk, I will present recent high-resolution N-body simulations of self-interacting dark matter and discuss their implications for a wide range of astrophysical observations. I will highlight new signatures associated with gravothermal collapse in dark matter halos and show how they may be detected through observations of strong gravitational lensing, stellar streams, and supermassive black holes, including the JWST Little Red Dots. These studies open new avenues for uncovering the particle physics of dark matter.

Speaker: 
Haibo Yu (University of California)
Place: 
KIAA-auditorium
Host: 
Fangzhou Jiang
Time: 
Wednesday, April 15, 2026 - 3:30PM to 4:30PM
Biography: 
Hai-Bo Yu is a Full Professor in the Department of Physics and Astronomy at the University of California, Riverside, and Deputy Director of the Center for Experimental Cosmology and Instrumentation. He received his Ph.D. from the University of Maryland in 2007 and held postdoctoral positions at the University of California, Irvine and the University of Michigan. His research lies at the interface of particle physics and astrophysics, focusing on probing new physics through astronomical observations. His work includes self-interacting dark matter, small-scale structure formation, and supermassive black holes. In recent years, he has shown that self-interacting dark matter can produce diverse halo structures from dwarf galaxies to galaxy clusters, offering an alternative to challenges faced by the standard cold dark matter paradigm. He has authored nearly 100 publications with over 14,000 citations.